Sélection - Instituto Europeo Del Bosque Cultivado

Silver Fir Bark Beetle

Pityokteines curvidens (Germar) (Coleoptera, Scolytidae)

Pityokteines curvidens lives almost exclusively on fir (Abies), only very rarely observed on Norway spruce.

The body is cylindrical, shiny, brown, covered with dense hair. Elytrae are with rows of punctures.
Males of this bark beetle are 2.7-3.2 mm long, and females are 2.0-2.6 long. The elytral declivity is with 3 teeth and 2 granules. The first tooth on the elytral declivity of males is pointed upward; two other teeth are hook-like and bended towards each other.
Females have small teeth. Hair on pronotum is only slightly longer than on frons. Eggs are small, whitish. The larva is up to 8 mm long.

Pityokteines curvidens is a species of great economic importance in fir plantations. Infestations have been reported all over Europe, where fir occurs.

One or two generations a year according to altitude and climatic conditions.
In April adults infest trees of different ages, usually starting from the upper part of the stem.
In July, the new adults emerge, going into the second generation.
The larvae of the second generation grow in the second half of the summer and then overwinter.
At higher altitudes or with less favorable climate, the majority of the population makes only one generation per year.

Stressed trees are more prone to attacks. Severe defoliations, prolonged drought, unharvested infested trees and excessive tree density are the main risk factors for Pityokteines curvidens infestations.

Pityokteines curvidens occurs throughout Europe and Anatolia, widespread in the whole range of the common fir distribution. Also introduced in Japan.

Preventive measurements, required especially in fir plantations, mainly concern the reduction of excessive tree densities and the harvesting of trees infested or susceptible to colonization.

Control requires the immediate harvesting of the attacked trees.
Trap logs are generally useless because insects tend to infest the upper part of standing trees and hardly infest trunks lying on the ground.
No measures of biological control of P. curvidens are known. Chemical control by synthetic pyrethroids should be allowed only on timber for commercial trade.

Outbreaks are likely to increase, especially in South Europe because of the increased summer droughts stressing fir and providing more favourable conditions for this secondary bark beetle.